1. Field of Invention
The invention herein described and claimed pertains generally to air cargo containers; more particularly, to a door closure apparatus for such an air cargo container.
2. Prior Art
Air cargo containers have been utilized for the transportation of cargo by aircraft for many years. The cargo is loaded first into the container, and the containers are then loaded into the aircraft. This was found to be far superior to loading the cargo directly into the cargo space of the aircraft. Far less time is required to load or unload the aircraft with a limited number of air cargo containers than would be required to load the cargo directly on the aircraft. Furthermore, because the cargo containers are designed and constructed to correspond to the interior dimensions of the air cargo space, the containers fit more snugly in the space and therefore do not shift during transportation. These and other advantages of the air cargo container have made the cargo container ubiquitous in the air cargo industry.
As with most machinery used in the air transportation industry, the two primary requisites in the design of a cargo container are that it be strong and that it be light. These goals, being inherently divergent, are difficult to obtain.
Favored air cargo containers are constructed almost entirely of aluminum, which provides the best mating of light-weight and strength. A cargo container has a base portion which more or less is an aluminum pallet. Usually the pallet is rectangular in shape. Attached to the base is an aluminum box having one or more doors. The box is typically constructed of two "hoops", resembling croquet wickets, each comprising two corner posts and a cross-piece member therebetween. There is a front hoop attached to the front of the base and a rear hoop attached to the rear of the base. Aluminum sheets are attached to the various corner posts and cross-piece members to complete the closure of the box, except for the front and/or rear which will become the door opening(s) for the container.
A consistent problem encountered in air cargo containers is with respect to the door closure apparatus. Again, strength, durability, and light-weight are desired characteristics in any door closure apparatus. The preferred door closure apparatus will be inexpensive, easy to use, easy to repair, weather proof, resistant to pilferage, strong, durable and light-weight, and, when closed, will support the structure when cargo shifts against the side sheets.
There are a number of door closure designs which are currently in use. Some utilize aluminum flaps of various designs which are hinged at the top of the door opening and at the center and are folded to a position at the container top when open. These designs suffer one or more of the drawbacks of expense, excess weight and/or poor performance.
Other designs incorporate fabric door closure means which are held in place in several different ways, including VELCRO self-sticking fabric at the sides. These designs, while typically inexpensive and light-weight, suffer from drawbacks in performance, strength and durability. Furthermore, these types of door closures are not sufficiently resistant to pilferage.
Therefore, there exists a need in the art for an improved air cargo container door closure apparatus.